146 lines
4.5 KiB
Python
146 lines
4.5 KiB
Python
# Copyright 2010 United States Government as represented by the
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# Administrator of the National Aeronautics and Space Administration.
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# Copyright 2011 Justin Santa Barbara
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import sys
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from eventlet import event
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from eventlet import greenthread
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from neutron.openstack.common.gettextutils import _
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from neutron.openstack.common import log as logging
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from neutron.openstack.common import timeutils
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LOG = logging.getLogger(__name__)
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class LoopingCallDone(Exception):
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"""Exception to break out and stop a LoopingCall.
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The poll-function passed to LoopingCall can raise this exception to
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break out of the loop normally. This is somewhat analogous to
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StopIteration.
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An optional return-value can be included as the argument to the exception;
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this return-value will be returned by LoopingCall.wait()
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"""
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def __init__(self, retvalue=True):
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""":param retvalue: Value that LoopingCall.wait() should return."""
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self.retvalue = retvalue
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class LoopingCallBase(object):
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def __init__(self, f=None, *args, **kw):
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self.args = args
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self.kw = kw
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self.f = f
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self._running = False
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self.done = None
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def stop(self):
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self._running = False
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def wait(self):
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return self.done.wait()
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class FixedIntervalLoopingCall(LoopingCallBase):
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"""A fixed interval looping call."""
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def start(self, interval, initial_delay=None):
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self._running = True
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done = event.Event()
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def _inner():
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if initial_delay:
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greenthread.sleep(initial_delay)
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try:
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while self._running:
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start = timeutils.utcnow()
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self.f(*self.args, **self.kw)
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end = timeutils.utcnow()
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if not self._running:
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break
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delay = interval - timeutils.delta_seconds(start, end)
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if delay <= 0:
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LOG.warn(_('task run outlasted interval by %s sec') %
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-delay)
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greenthread.sleep(delay if delay > 0 else 0)
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except LoopingCallDone as e:
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self.stop()
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done.send(e.retvalue)
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except Exception:
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LOG.exception(_('in fixed duration looping call'))
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done.send_exception(*sys.exc_info())
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return
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else:
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done.send(True)
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self.done = done
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greenthread.spawn_n(_inner)
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return self.done
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# TODO(mikal): this class name is deprecated in Havana and should be removed
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# in the I release
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LoopingCall = FixedIntervalLoopingCall
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class DynamicLoopingCall(LoopingCallBase):
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"""A looping call which sleeps until the next known event.
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The function called should return how long to sleep for before being
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called again.
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"""
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def start(self, initial_delay=None, periodic_interval_max=None):
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self._running = True
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done = event.Event()
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def _inner():
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if initial_delay:
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greenthread.sleep(initial_delay)
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try:
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while self._running:
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idle = self.f(*self.args, **self.kw)
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if not self._running:
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break
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if periodic_interval_max is not None:
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idle = min(idle, periodic_interval_max)
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LOG.debug(_('Dynamic looping call sleeping for %.02f '
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'seconds'), idle)
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greenthread.sleep(idle)
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except LoopingCallDone as e:
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self.stop()
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done.send(e.retvalue)
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except Exception:
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LOG.exception(_('in dynamic looping call'))
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done.send_exception(*sys.exc_info())
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return
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else:
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done.send(True)
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self.done = done
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greenthread.spawn(_inner)
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return self.done
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